1. Field of the Invention
The present invention relates to a hand-held power tool such as, e.g., a combination hammer, having more than two different modes of operation.
2. Description of the Prior Art
A multi-purpose or combination hammer has, in addition to a rotary drive for producing a rotational movement, another drive, e.g., a percussion drive.
In one of the operational modes of the combination hammer, the rotary drive is separated from the working tool-receiving spindle, with the spindle being secured to hammer housing without a possibility of rotation relative to the housing.
German Publication DE 27 28 961 discloses a combination hand-held power tool which has a change-over clutch displaceable along the spindle and connected with the spindle for joint rotation therewith. The change-over clutch is displaced with a mode selector switch and has one of its end faces connectable with a pinion of the power tool drive and the other of its end faces connectable with a pinion secured to the tool housing. In the later case, the spindle becomes connected with the housing without a possibility of rotation relative thereto.
German Publication DE 19 38 660 discloses a hammer drill provided with a clutch pusher, which extends transverse to the tool spindle and which is displaced by a mode selector switch for changing the rotational speed of the spindle. An engagement cam, which is formed as a pin and is associated with the clutch pusher, connects alternatively, upon displacement of the clutch pusher, two different, step-forming, pinions of the tool drive with a bevel pinion that engages a pinion supported on the tool spindle. A fixed connection of the spindle with the housing without possibility of rotation relative thereto does not find any application in the hammer drill.
Each of the above-discussed publication discloses a hand-held power tool with two modes of operation.
Accordingly, an object of the present invention is to provide a hand-held power tool with more than two modes of operation which can be easily realized.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a hand-held power tool having at least three modes of operation and including a clutch pusher at least partially located in the tool housing and fixedly connected with a bevel gear for joint rotation therewith, with the bevel gear engaging a bevel gear supported on the drive spindle. The tool includes at least one engagement cam connecting the clutch pusher with driving gears for joint rotation therewith, with a possibility of axial displacement of the clutch pusher relative thereto, in the first and second modes of operation. According to the present invention, in the third mode of operation, which is obtained by displacement of the clutch pusher, the spindle is stopped without a possibility of rotation relative to the housing with the engagement cam engaging in a recess provided in the housing. Advantageously, the hand-held power tool has a fourth mode of operation in which the clutch pusher occupies a position in which the engagement cam rotates in a free space, with the spindle being freely rotatable.
Advantageously, the fourth position of the clutch pusher, which corresponds to the fourth mode of operation, is located between the second and third positions thereof.
Advantageously, the first and second positions of the clutch pusher correspond to first and second modes of operation in which the spindle rotates with two different rotational speeds.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to is construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments when read with reference to the accompanying drawings.